Bone contraints fail to append

I have created an armature with a number of detailed bone contraints - mostly “copy rotations” with axis limits. When I attempt to append the new armature from its .blend file to the figure mesh file, the armature appears but is missing all those bone contraints.

Is this a program error or am I missing something? Thanks for any clues.


I discovered that the problem occurred AFTER the append. I had accidentally deleted some bones by leaving x-axis mirroring on when I was deleting bones on one side - so accidentally deleted them on both sides, and then used CTRL Z to bring them back - CTRL Z failed to bring back the contraints. I made this mistake twice, so I was sure it was the append function. Conclusion: if I accidentally delete a bone using mirror, when I undo the deletion, the contraints will be lost